Whooping cough (pertussis) facts

Whooping cough commonly affects infants and young children but can be prevented by immunization with the pertussis vaccine.

Young infants are at greatest risk for complications and even death from the disease.

Adults may develop whooping cough as their immunity from vaccines wears off over time.

Clinical symptoms occur in three stages; the characteristic bursts of coughing are observed in the second, or paroxysmal, stage.

Antibiotics can help reduce the severity of the disease when administered early in the course of the disease.

Secondary bacterial pneumonia is the most common complication of whooping cough.

What is whooping cough? What is the history of whooping cough?

Whooping cough is a bacterial upper respiratory infection that leads to episodes of violent coughing. The disease is named for the characteristic sound produced when affected individuals attempt to inhale; the whoop originates from the inflammation and swelling of the laryngeal structures (voice box) that vibrate when there is a rapid inflow of air during inspiration. The whoop in not often appreciated in infants and toddlers but will be recognized in older children, teens, and some adults (rarely). Infants and toddlers are more likely to have recurrent and frequent episodes of violent cough which may cause facial cyanosis (blue skin discoloration) and rarely apnea (cessation of breathing). Whooping cough is highly contagious.

The first outbreaks of whooping cough were described in the 16th century. The bacterium responsible for the infection, Bordetella pertussis, was not identified until 1906. In the pre-vaccination era (during the 1920s and '30s), there were over 250,000 cases of whooping cough per year in the U.S., with up to 9,000 deaths. In the 1940s, the pertussis vaccine, combined with diphtheria and tetanus toxoids (DTP), was introduced. By 1976, the incidence of whooping cough in the U.S. had decreased by over 99%.

During the 1980s, however, the incidence of whooping cough began to increase and has risen steadily, with epidemics typically occurring every three to five years in the U.S. In the epidemic of 2005, 25,616 cases were reported according to the U.S. Centers for Disease Control and Prevention (CDC). In 2008, over 13,000 cases of whooping cough were reported in the U.S., resulting in 18 deaths. In 2010, which included an epidemic in California (see below), 27,550 cases of pertussis were reported nationwide.

In 2012, over 48,000 cases of pertussis infection were reported in the U.S., the highest number of reported cases in one year since 1955.

What causes whooping cough?

Whooping cough is caused by an infection by a bacterium known as Bordetella pertussis. The bacteria attach to the lining of the airways in the upper respiratory system and release toxins that lead to inflammation and swelling.

Most people acquire the bacteria by breathing in the bacteria that are present in droplets released when an infected person coughs or sneezes.

Is whooping cough contagious?

The infection is very contagious is often is spread to infants by family members or caregivers who may be in the early stages of infection and not realize that they are suffering from whooping cough.

What is the contagious period for whooping cough?

A person infected with pertussis is highly contagious (can spread the infection to others) from the onset of symptoms to around three weeks after the onset of the coughing episodes. If antibiotic treatment is given, the contagious period is reduced to about five days.

What are risk factors for whooping cough?

Whooping cough can infect anyone. Unimmunized or incompletely immunized young infants are particularly vulnerable to the infection and its complications, which can include pneumonia and seizures. Infants who contract whooping cough may also experience episodes of apnea (cessation of breathing). The infection occurs worldwide, even in countries with well-developed vaccination programs. Adults may develop pertussis because the immunity from childhood vaccinations can wear off over time.

How long does the whooping cough vaccine last?

Receiving the vaccine or having the disease does not ensure lifelong protective immunity against pertussis. Immunity to the bacteria decreases after five to 10 years following administration of the vaccine. Therefore older children, adolescents and adults are at risk of becoming infected with pertussis and need revaccination. Vaccinating adults is also important because adults can serve as a source of infection for infants, who are at particular risk of having severe illness and serious complications from pertussis.

Those who have been vaccinated and still become ill, however, have a lower risk of complications and often experience less severe symptoms. In most cases, the duration of the cough is shorter and coughing fits are less frequent than in unvaccinated people.

What is the incubation period for whooping cough?

The incubation period, or the time frame from exposure to the causative bacteria and development of symptoms, is longer than that for the common cold and most upper respiratory infections. Typically, signs and symptoms develop within seven to 10 days of exposure to pertussis, but they may not appear for up to three weeks after the initial infection.

What are whooping cough symptoms, signs, and stages?

The first stage of whooping cough is known as the catarrhal stage. In the catarrhal stage, which typically lasts from one to two weeks, an infected person has symptoms characteristic of an upper respiratory infection, including

It is important to note that particularly during this early phase of infection, individuals may believe they have a common cold and may not be aware that they are infected with the pertussis bacterium.

The cough gradually becomes more severe, and after one to two weeks, the second stage begins. It is during the second stage (the paroxysmal stage) that the diagnosis of whooping cough usually is suspected. The following characteristics describe the second stage:

There are bursts (paroxysms) of coughing, or numerous rapid coughs, apparently due to difficulty expelling thick mucus from the airways in the lungs. Bursts of coughing increase in frequency during the first one to two weeks, remain constant for two to three weeks, and then gradually begin to decrease in frequency.

At the end of the bursts of rapid coughs, a long inspiratory effort (breathing in) is usually accompanied by a characteristic high-pitched whoop sound for which the disease is named.

During an attack, the individual may become cyanotic (skin and mucous membranes may turn blue) from lack of oxygen.

Children and young infants appear especially ill and distressed.

Vomiting (referred to by doctors as post-tussive vomiting) and exhaustion commonly follow the episodes of coughing.

The person usually appears normal between episodes.

Paroxysmal attacks occur more frequently at night, with an average of 15-24 attacks per 24 hours.

The paroxysmal stage usually lasts from one to six weeks but may persist for up to 10 weeks.

Infants under 6 months of age may not have the strength to have a whoop, but they do have paroxysms of coughing.

The third stage of whooping cough is the recovery or convalescent stage. In the convalescent stage, recovery is gradual. The cough becomes less paroxysmal and usually disappears over two to three weeks; however, paroxysms often recur with subsequent respiratory infections for many months.

How long does whooping cough last?

It can take up to three weeks after exposure to develop symptoms, although symptoms usually develop within five to 10 days after infection. The paroxysmal stage, characterized by the coughing fits, usually lasts from one to six weeks but can last for up to 10 weeks. The third and final stage (convalescent stage) lasts about two to three weeks.

What does whooping cough sound like?

As mentioned above, the characteristic cough of pertussis occurs in the second or paroxysmal stage of the illness. There is a series or burst of rapid coughs. At the end of these coughs, a long inspiratory effort (breathing in) is usually accompanied by a high-pitched whoop sound for which the disease is named.

How is whooping cough transmitted?

Whooping cough is highly contagious and is spread among people by direct contact with fluids from the nose or mouth of infected people. People contaminate their hands with respiratory secretions from an infected person and then touch their own mouth or nose. In addition, small bacteria-containing droplets of mucus from the nose or lungs enter the air during coughing or sneezing. People can become infected by breathing in these drops.

Can adults get whooping cough?

Although whooping cough is considered to be an illness of childhood, adults may also develop the disease even if they were vaccinated as children. Because immunity from the pertussis vaccine decreases over time but does not necessarily disappear, adults who do become infected may have retained a partial degree of immunity against the infection that results in a milder illness. Although the illness usually is milder in adults than in children, the duration of the paroxysmal cough lasts just as long as in children. The characteristic whoop that occurs after paroxysmal bouts of coughing is recognized in only 20%-40% of adults with whooping cough.

Whooping cough in adults is more common than usually appreciated, accounting for up to 7% of adult illnesses that cause coughing each year. Infected adults are a reservoir (source) of infection for children, so it is particularly important that all family members and caregivers of young infants be properly vaccinated.

What specialists treat whooping cough?

Whooping cough may be treated by primary-care providers, including internists, pediatricians, and family medicine specialists. In some cases, infectious-disease specialists may be consulted.

How do health-care professionals diagnose whooping cough?

When a patient has the typical symptoms of whooping cough, the diagnosis can be made from the clinical history. However, the disease and its symptoms, including its severity, can vary among affected individuals. In cases in which the diagnosis is not certain or a doctor wants to confirm the diagnosis, laboratory tests can be carried out. Culture of the bacterium Bordetella pertussis from nasal secretions can establish the diagnosis. Another test that has been used to successfully identify the bacterium and diagnose whooping cough is the polymerase chain reaction (PCR) test that can identify genetic material from the bacterium in nasal secretions.

What is the treatment for whooping cough?

Antibiotics directed against Bordetella pertussis can be effective in reducing the severity of whooping cough when administered early in the course of the disease. Antibiotic therapy can also help reduce the risk of transmission of the bacterium to other household members as well as to others who may come into contact with an infected person. Unfortunately, most people with whooping cough are diagnosed later with the condition in the second (paroxysmal) stage of the disease.

Treatment with antibiotics is recommended for anyone who has had the disease for less than three to four weeks. Azithromycin (Zithromax), clarithromycin (Biaxin), erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone), and sulfamethoxazole (Bactrim, Septra) are antibiotics that have been shown to be effective in treating whooping cough. It is unclear whether antibiotics have any benefit for people who have been ill with whooping cough for longer than three to four weeks, although antibiotic therapy still is often considered for this group. There is no proven effective treatment for the paroxysms of coughing that accompany whooping cough.

Antibiotics also are routinely administered to people who have had close contact with an infected person, regardless of their vaccination status.

Do not give an infected child cough syrup or cough medicines unless instructed to do so by a doctor. They have not been shown to be of benefit, and they may cause sedation that leads to worsened outcomes.

What is the prognosis for whooping cough?

The infection gradually resolves over a period of weeks, but the coughing paroxysms can persist for several months. The prognosis is worse when complications such as bacterial pneumonia (see below) develop in a person with whooping cough. Young infants are at highest risk of serious complications and even death from whooping cough.

Data indicate that secondary pneumonia occurs in about one out of every 20 infants with whooping cough, and one out of 100 affected infants develop convulsions. Most deaths from whooping cough have occurred in children who have not been vaccinated or who are too young to have received the vaccine.

What are possible complications of whooping cough?

The most common complication and the cause of most whooping cough-related deaths is secondary bacterial pneumonia. (Secondary bacterial pneumonia is bacterial pneumonia that follows another infection of the lung, be it viral or bacterial. Secondary pneumonia is caused by a different virus or bacterium than the original infection.) Young infants are at highest risk for whooping cough and also for its associated complications, including secondary pneumonia. Other possible complications of whooping cough, particularly in infants less than 6 months of age, include seizures, encephalopathy (abnormal function of the brain due to decreased oxygen delivery to the brain caused by the episodes of coughing), reactive airway disease (asthma), dehydration, hearing loss, and malnutrition. Other complications that have been reported in adults include weight loss, loss of bladder control, and rib fractures from coughing.

Is it possible to prevent whooping cough? Is there a whooping cough vaccine?

Whooping cough commonly affects infants and young children but can be prevented by immunization with the pertussis vaccine. Pertussis vaccine is most commonly given in combination with the vaccines for diphtheria and tetanus. (Pertussis is the "P" in the DTaP combination inoculation routinely given to children, and the "p" in the Tdap vaccine administered to adolescents and adults.) Since immunity from the pertussis vaccine wears off with time, many teenagers and adults get whooping cough.

For maximum protection against pertussis, children need five DTaP shots. The first three vaccinations are given at 2, 4, and 6 months of age. The fourth vaccination is given between 15-18 months of age, and a fifth is given when a child enters school, at 4-6 years of age. Preteens going to the doctor for their regular checkup at 11 or 12 years of age should get a dose of the Tdap booster, and adults who didn't get Tdap as a preteen or teen should get one dose of Tdap. The easiest way for adults to ensure immunity is to get the Tdap vaccine instead of their next regular tetanus booster. (The Td shot is recommended every 10 years.)

The vaccine has been deemed safe for pregnant women. To protect their infants, most pregnant women who were not previously vaccinated with Tdap should get one dose of Tdap during the late second trimester or third trimester of pregnancy. The CDC recommends that women get the Tdap vaccine during each pregnancy. If not administered during pregnancy, women should get the vaccine postpartum before leaving the hospital or birthing center. Getting vaccinated with Tdap is especially important for mothers and families with new infants as well as all people caring for newborns. When a woman receives the Tdap vaccine during pregnancy, the antibodies she develops to the Bordetella pertussis bacterium are transferred to the infant, providing some additional protection to the infant before the baby can be fully vaccinated.